The present invention relates generally to the lining of pipes with a tubular material and, more particularly to the relining of a particular portion of a pipe.
The most common underground pipeline is a sewer pipe which conveys wastewater from residences and industry through a wastewater collection system to a wastewater treatment facility. Sewers are often buried underground and located underneath streets and roadways. Portions of the sewer system may become cracked or broken over time due a number of factors. Shifting of the earth, secondary surface loadings and weather conditions are examples of external factors which may affect the integrity of sewer pipes as well as other subterranean pipes. These external factors may result in broken pipe sections which compromise the ability and effectiveness of the sewer system to accomplish its collection and conveyance functions of wastewater.
Apart from the external factors set forth above, sewers and other pipelines may also have their effectiveness compromised by internal factors. For example, the inner surface of a sewer pipe may become eroded or roughened from continuous contact with wastewater and abrasive material suspended therein. Erosion of the interior surfaces of any fluid-conveying pipe results in an increase in the pipe's roughness coefficient. This coefficient is a measure of the resistance to fluid flow by the pipe. The greater the roughness coefficient, the greater the head loss experience by fluid passing through the pipe. Eroded pipes therefore make it more difficult to convey wastewater than pipes as originally designed and installed. This problem may be cured by relining or replacing the sewer pipe. Sewer pipes need to be replaced or relined on a regular schedule in order to reclaim the original design parameters of the sewer system.
It is known in the art that the above problems may be effectively cured by replacement or repair of the compromised portion of sewer pipe. Excavation of the area surrounding the sewer pipe and replacement of the broken portions is one solution, but it is a very expensive and labor intensive solution. This type of repair is also an inconvenience to residents living in the area and utilizing those roadways overlying the compromised area.
Another solution which is less expensive in labor and intensive is in situ relining of the sewer pipes. In situ relining methods typically utilize a resin-coated liner which is inserted into the existing sewer pipeline and unrolled against the sewer pipe. The unrolled liner is held against the existing sewer pipe while the resin cures to form a new pipe lining within the existing pipe which provides a new and relatively smooth interior surface having a low roughness coefficient which rivals or better than that of the original sewer pipe. These type liners also protect the existing pipe from attack by many chemicals found in wastewater fluid and reinforces the existing pipe to existing subterranean external loads imposed upon the pipes. These relining methods are well described in the patent literature.
One such relining method is described in U.S. Pat. No. 4,876,921 and utilizes a plastic liner known as the NuPipe.RTM.. The NuPipe.RTM. liner is an extruded thermoplastic sleeve which is heated to soften the liner and pulled through the sewer pipe. A rounding device is then propelled through the plastic liner to force the liner outwardly against the existing pipeline. This type of relining process is costly and the liner does not expand to a significantly large degree so that the installer needs to have a variety of different diameter liners on hand as inventory to effectively match the inner diameters of existing pipes.
Other methods described in the patent literature include the use of a woven textile liner laminated with multiple resin coatings. This type of liner and its method of installation of this type liner are described in U.S. Pat. No. 4,600,615, which issued Jul. 15, 1996, which discloses a pipe relining material consisting of a woven, air-impervious textile jacket which has an outer resin coating consisting of multiple polyester resin layers laminated to each other. These woven liners are inserted into an existing sever pipe and inflated against the existing sewer pipe walls by fluid pressure. Because of their woven construction, these lines do not significantly expand against the existing pipe walls and therefore the installer needs to carry a large amount on inventory on hand to fit the diameter of the pipe being repaired.
The patents identified above all describe liners which are commonly installed in pipes and extend from one accessway, or manhole, to another accessway. The length of the subterranean pipeline between these opposing accessways may range anywhere from 50 to 500 feet. Quite often, in such a large extent of pipe only one particular section of the pipe is compromised and needs to be relined. The prior art does not suggest an effective means of spot repair, i.e., repairing only the compromised section of the pipe, but rather suggests either relining the entire length of the sewer pipe or relining the sewer pipe from the nearest accessway to the compromised pipe section. Either of these two approaches results in an increased repair cost and usage of more relining material than is necessary.
The present invention therefore concerns itself with an apparatus and a method for reliably performing such spot repairs, in which only the compromised pipe section is repaired. The present invention represents a significant advancement over the prior art in that it permits the insertion into the existing pipe of a preselected length of a new pipe lining material and conveyed through the pipe until the lining material is located adjacent the compromised section pipe. The lining material is subsequently contacted against the inner surface of the existing pipe to form a new lining at the compromised pipe section only. By reliably locating the new liner material proximate to the compromised section and retaining it in place while the new lining material is cured in place, the present invention significantly reduces the expense and time and labor required to perform such spot repairs. Additionally, the present invention provides for the introduction into an existing pipeline of a pipe lining material which is impregnated with resin in a "clean" fashion, in which the risk of either contamination of the resin or contact between the resin-impregnated liner and the existing pipe or the individuals installing same is substantially eliminated. It further allows for accurate positioning of the new lining material at the compromised pipe section.
In accordance with one principal aspect of the present invention, a new pipe lining material is impregnated with a curable resin and is held in place within a carrier which conveys the resin-impregnated lining material to the compromised pipe section without contacting the walls of the existing pipe which might remove resin therefrom during positioning of the lining material within the pipe. A flexible envelope, or inflation bladder, which forms an extension of the carrier and provides a support for the lining material during installation when the lining material is everted out of the carrier. This flexible envelope expands radially under fluid pressure as it everts axially out of the carrier and into contact with the pipe wall inner surface.
In another principal aspect of the present invention, the lining material is attached to the inflation bladder by means of a frangible connection which fixes the position of the lining material with respect to the carrier the compromised pipe section. This frangible connection has a strength sufficient to withstand the eversion of the lining material out of the launching device, yet is weak enough to break after the lining material has cured and the carrier is removed from the pipe. This frangible connection permits the flexible envelope to anchor the tubular lining in position during installation and support it in place within the compromised pipe section during curing.
In accordance with yet another principal aspect of the present invention, the flexible envelope is inverted in the carrier during insertion of the carrier into the existing pipeline and the envelope is formed from a urethane-coated scrim which is capable of limited expansion under pressure against the pipe wall.
In still yet another principal aspect of the present invention, the carrier includes an endcap having means for positioning the carrier within the pipe, fluid entrance and exit means and an inflation bladder stop means. The carrier has an open eversion end which includes a collar which engages the flexible envelope and a plurality of flexible cover members, in the form of flaps which form a flexible cover portion over the collar to protect the attachment between the inflation bladder and the carrier and to assist the carrier to negotiate bends and other internal configurations of the existing pipe.
Accordingly, it is an object of the present invention to provide an improved apparatus and method for the relining of pipes.
It is another object of the present invention to provide an apparatus for the insertion and installation of a new liner into an existing pipe which is particularly suitable for the spot repair of compromised sections of a given pipeline, wherein the liner is introduced into the existing pipe by means of a carrier which encloses the liner and protects it from contact with the surrounding pipe walls until the liner is in its desired location within the existing pipe.
It is still a further object of the present invention to provide a method for the relining of subterranean pipes in which a pipe liner is secured to an inflation bladder, coated with resin and encapsulated within a positioning element, the positioning element then being inserted into an existing pipe and fluid being introduced under pressure into the positioning element to cause the inflation bladder and the liner secured thereto to evert outwardly from within the positioning element into a placement position near the compromised pipe section, the inflation bladder expanding radially in response to the fluid pressure and urging the liner into contact against the pipe wall, and subsequently removing the inflation bladder and positioning element from the pipe.
It is still yet a further object of the present invention to provide a method for the relining of pipes in which a resin-coated liner is introduced into an existing pipe and cured in place, the method including the steps of forming a liner-bladder assembly in which a pipe liner is anchored on a inflatable bladder by frangibly attaching the liner to the inflatable bladder, the liner being impregnated coated with a curable resin; the liner-bladder assembly being enclosed within an elongated carrier element; the carrier element being introduced into the pipeline; an inflating medium being introduced into the carrier element under pressure to cause the bladder-liner assembly to evert out of the carrier element into the compromised pipe section, and thereby to further cause the inflatable bladder and liner to expand radially within the pipe into contact with the inner surface of the pipe wall; the resin being allowed to cure so as to form a solid new pipe lining within the existing pipe; and, the carrier element and bladder being subsequently withdrawn from the pipe, leaving the cured liner in place within the pipe.
Yet another object of the present invention is to provide novel inflation envelope for use in the installation of lining materials in pipelines, the inflation envelope having opposed sealed and open ends adapted for engagement to an insertion member, the inflation envelope being formed from a flexible polymeric material into an elongated tube, the inflation envelope further having means for frangibly anchoring a portion of the liner to the inflation envelope.
A still further object of the present invention is to provide an apparatus for installing a new liner within an existing pipeline comprising an elongated, flexible lining material support means, an elongated liner positioning means, the support means being interconnected to the liner positioning means at an open end thereof so as to permit the support means to be inverted into and everted out of the liner positioning means, the liner positioning means further having a plurality of protective cover members disposed near its open end which protect the support means within the liner positioning means during insertion of the liner positioning means into the pipe, the liner positioning means further having means for limiting the eversion of the support means out of the liner positioning means, the support means further having frangible attachment means adapted to provide a frangible connection between the support means and the pipe liner to hold the liner in place during installation yet separate during removal of the launching means from the pipe while leaving the new liner in place within the pipe.
These and other objects, features and advantages of the present invention will be apparent through a reading of the following detailed description, taken in conjunction with accompanying drawings, wherein like reference numerals refer to like parts.